LibreLink MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, indicating a safe read operation. The description adds valuable context beyond annotations by specifying the source ('FreeStyle Libre sensor'), the return format (glucose value in mg/dL, trend direction, target range status), and the real-time nature of the data. It doesn't mention rate limits or authentication needs, but with annotations covering safety, this provides good behavioral insight.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences: the first states the action and return values, the second provides usage guidance. Every word earns its place with no redundancy or fluff, making it highly efficient and front-loaded with essential information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's low complexity (0 parameters, read-only), annotations cover safety, and no output schema exists, the description does well by explaining the return format (value, trend, range status) and usage context. It could mention data freshness or sensor connectivity, but it's largely complete for this tool type.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 0 parameters with 100% coverage, so no parameter documentation is needed. The description appropriately doesn't discuss parameters, focusing instead on the tool's purpose and output. This aligns with the baseline expectation for zero-parameter tools.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the specific action ('Get'), resource ('most recent glucose reading from your FreeStyle Libre sensor'), and distinguishes from siblings by focusing on real-time current reading rather than historical data (get_glucose_history), statistics (get_glucose_stats), or trends (get_glucose_trends). It explicitly mentions what data is returned, making the purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly states when to use this tool: 'Use this for real-time glucose monitoring.' This provides clear context for choosing this tool over alternatives like get_glucose_history (for historical data) or get_glucose_trends (for trend analysis), making it easy for an agent to select the appropriate tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.